1. Field of the Invention
The invention concerns an articulated clamp connector for interconnecting pipes, cables, etc. where metal seals are used in the connecting surfaces. The clamp connector is preferably intended for subsea applications where there are high requirements on reliability and integrity.
2. Description of the Related Art
Interconnecting pipes, etc. in a subsea (underwater) environment place severe demands on the connection arrangement, both with regard to the operation of the connection arrangement during interconnection and disconnection, and also the function of the connector system, i.e. reliability and tightness in the connector, during use and in connection with, for example, deep sea activities and the transport of oil and gas under high pressure.
A need with such connectors is, therefore, to meet both the requirement of simple operation, that is, the mounting/dismounting of the connector, while at the same time meeting the reliability requirement for the connector during use.
There are innumerable variants of mechanical connectors within this field. These connectors can be divided into two groups. Group 1 consists of segment/collet type connectors and group 2 consists of clamp type connectors. Both connector groups have the common goal of seeking to achieve an axial pretension between the connector flanges where segments or clamps respectively generate this force. This is achieved through a wedge effect between one or more conical outer surfaces (flange profile) arranged on parts that are to be connected and opposite surfaces in the connector segment or clamps, where the latter is sought to be displaced by a radial force produced by the mechanics in the connector. Both these groups have the following properties.
Group 1 is characterized by the segment being run mechanically, either by an outer cam ring that causes rotation of a set of collet fingers, or directly driven locking segments, both based on radial running of the mentioned segments. There is significant interaction between a connector house of one of the flanges and the other connection flange, making it necessary to perform an axial joining movement between the flanges before the connection itself can be performed. This movement must be provided by use of mechanical flexibility in the pipe system, or alternatively, in some other way. The main advantage of this group of connectors is an even distribution of the pretension force. The main disadvantage is a deep interaction (engagement), with corresponding limited possibility for replacing metal gaskets on site, for example, by use of a remotely operated vehicle (ROV), as well as a correspondingly costly embodiment of the connector house.
Group 2 is characterized by the clamps, in 180xc2x0 design (in two parts) or 60xc2x0 design (in three parts) hinged/bolted, being operated with a screw-based mechanism where only parts of the clamp move radially towards the flange center. The main advantage with this solution is that a hinged variant entails reduced requirements of the connecting movement, as well as that an emergency opening can be performed with cutting only a single bolt. The main disadvantage is that the loss of friction in the arrangement between the flanges and the clamps disrupts the distribution of axial tension. This results in the clamp connector having to be over-dimensioned to compensate for low mechanical efficiency. The function required from the clamp is complex and must be made subject to a compromise. Thus, it is typically a contradictory requirement that must be met with regard to the clamp""s structural stiffness, xe2x80x9cstiff enoughxe2x80x9d to carry tangential forces, xe2x80x9csoft enoughxe2x80x9d at reduced bending resistance, to offer resiliency when tightening involves placing the clamps in a smaller circle segment. This may be solved by making several linked clamp elements, according to the xe2x80x9cbicycle chain principlexe2x80x9d.
The articulated clamp connector according to the present invention seeks to combine the advantages with the seals according to above mentioned groups 1 and 2 connectors.
The aim of the present invention is, therefore, to achieve a connector that simply can be mounted around a joint where, for example, two pipes that are to be connected only to a minimal degree, need be moved apart to apply the connector. Furthermore, the connector shall be easy to operate. That is, it shall be able to be easily locked around the connection and in the same manner, securely and easily opened, for example, in an emergency situation. The connection must be reliable and leak free, as an even distribution of pretension must be achieved between the connection""s metal meeting surfaces.
A very important aim for the clamp connector according to the present invention is to produce mechanical tension between two flanges so that a metallic sealing ring creates a tight connection between the flanges, especially for this purpose. The operation is reversible and may be performed manually or with the use of automated tool systems, the latter in connection with underwater (subsea) operations without the use of divers.
More specifically, the aim of this invention is a clamp connector consisting of a mechanical arrangement containing a split or whole tangential working ring for activating radial pawl, the purpose of which is to achieve even distribution of pretension around a flange pair, which is necessary to initiate and maintain pretension in a metal seal connection.
The above mentioned goals are achieved according to the invention by an articulated clamp connector for connecting pipes, cables, etc., preferably subsea, where the interconnecting ends of the pipes are constructed with joining flanges with outer conical surfaces which interact with opposite surfaces of the clamp, whereby the connecting flanges are pressed against each other during the connection, bringing about a metal seal between the flanges, in that the clamp connector constitutes a set of outer articulated clamp halves placed around the connecting flanges, and a first tightening bolt for closing of the outer clamp halves around the connecting flanges. The clamp connector further comprising a split activating ring slideably arranged within the outer clamp halves, a second tightening bolt arranged for tangential movement of the split activating ring, a number of spring elements arranged between the split activating ring and locking segments placed in grooves, respectively, in the inner part of the split activating ring and the outer part of the locking segments, whereby tangential movement of the split activating ring by use of the second tightening bolt brings about radial movement of the locking segments and the locking segments inside conical surfaces force the connecting flanges together, thus achieving an even distribution of pretension around the connecting flanges to initiate and maintain pretension in the metal seal connection.